Re: serial vs parallel port

I realize I'm jumping in a little bit late on this thread, but I have
been doing a lot of digging for information lately to see how to
convert a lathe to cnc operation, and more, to figure out what peices
of code I need to tell it what to do. During this, I noticed some
controllers for sale on ebay that used serial control and I wound up
having the same question. The only thing I could think of was,
giveing each serial device the paramaters for the axis it was to
move, including the feed rates, and then having them all start upon
seeing a synch line.. ie.. just pulling down a single bit of the
parallel port that they are all tied to. The disadvantage being that
it would be a bit more difficult to have them do look ahead curve
smoothing for you.

RIck

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Don Rogers <Don@C...> wrote:
>
> >Dear group can EMC use the RS232 port (serial) instead of the
printer
> >port?
>
> This bring us a question I have had for a few months now. How can
you
> truly synchronize multiple axis when driving them individually via
a serial
> interface, IE from an indexer card vs a step/direction approach
from a
> parallel port. The serial approach indicates giving one axis it
> instructions and the going to the next axis and giving it it's
instructions.
>
> It seems to me that the indexer approach of sending serial commands
to a
> single axis, however fast that can happen would lead to a bunch of
> individual movements not necessarily related to the goal at hand..
>
> Having looked at this for a while, I ended up stripping the indexer
cards
> from my drivers to go to a step direction from a single port
approach in
> the hopes that a single Command structure would be better than a
> discriminate command structure..
>
> Any discussion on this???
>
> Don